In Process Bank transactions the system does a very good job now with automatic rules. When selecting Auto Match, if the system does not find a match it selects Create Transaction as if the end user will be doing this. However if the end user creates a rule and then clicks Auto Match again, it won't process the existing transactions that did not match because it has selected Create Transaction. So you either have to go to each transaction and unselect which takes time (for the end user, plus the performance is slow), or lose all of the work you have done.
Unless their is a good reason, when a transaction fails to Auto Match, do not select Create Transaction. It will save end users a lot of time continually building rules and then applying them against the remaining trans to do.